KR102111502B1 - Organic light emitting diode display device - Google Patents

Abstract

The present invention discloses an organic light emitting display device. The disclosed organic light emitting diode display device includes an organic light emitting element formed on a substrate and emitting light; A reflective polarizing film formed on the organic light-emitting device, a reflective polarizing film (dual brightness enhancement film, DBEF); A cholesteric liquid crystal (CLC) film formed on the reflective polarizing film; A phase retardation plate formed on the cholesteric liquid crystal film; And it characterized in that it comprises a polarizing plate formed on the phase retardation plate.
Therefore, the organic light emitting display device according to the present invention can remove reflection of external light, thereby realizing black satisfactorily, improving contrast, and forming light absorbed by the polarizing plate, and maximizing emission It can improve the efficiency, reduce the power consumption, and improve the life of the device.

Description

Organic light emitting diode display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device that improves device efficiency by including a polarizing plate that does not emit light from outside.

In recent years, as the era of full-scale informatization, the display field for visually expressing electrical information signals has rapidly developed, and in response, various various flat panel display devices with excellent performance of thinning, lightening, and low power consumption ( Flat Display Device) has been developed to rapidly replace the existing cathode ray tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), an organic light emitting display (OLED), an electrophoretic display (EPD), and an electrical paper display (EPD). Plasma Display Panel device (PDP), Field Emission Display device (FED), Electro luminescence Display Device (ELD) and Electro-Wetting Display (EWD) And the like. These commonly use a flat panel display panel that implements an image as an essential component, and the flat panel display panel includes a pair of substrates that are face-to-face bonded with a layer of a unique light emitting material or a polarizing material therebetween.

An organic light emitting diode display device, which is one of such flat panel display devices, includes an organic light emitting device, which is a self-light emitting device, and thus, a separate light source used for a liquid crystal display device, which is a non-light emitting device, is not required. Light and thin is possible. In addition, it has a better viewing angle and contrast ratio than a liquid crystal display device, and is also advantageous in terms of power consumption, DC low voltage driving is possible, response speed is fast, and internal components are solid, so it is strong against external shock and has a wide operating temperature range. It has advantages.

The organic light emitting device is a device that emits light by depositing an organic light emitting layer formed of an organic material between an anode made of ITO or the like and a cathode made of aluminum (Al) on a glass substrate. When a voltage is applied between the anode and the cathode of the organic light emitting device, holes are injected from the anode, electrons are injected from the cathode, and then meet at the light emitting layer through movement to generate excitons. The organic light emitting display device may use light emitted while the generated exiton falls to the ground state.

At this time, the conventional organic light emitting display device includes at least one electrode capable of reflecting light, and has a problem of reflecting light flowing from the outside. Therefore, it is difficult to implement black due to reflection of external light, and there is a disadvantage that the contrast is lowered.

In order to solve this problem, there is a configuration in which a polarizing plate and a phase retardation plate are disposed to suppress reflection of external light. However, it is difficult to completely block external light. At this time, when a polarizing plate and a phase retardation plate are disposed to suppress reflection of external light, there is a problem in that a considerable portion of the light generated in the organic light emitting layer is also lost.

An object of the present invention is to provide an organic light emitting display device capable of removing reflection of external light, realizing black, and improving contrast.

In addition, another object of the present invention is to provide an organic light emitting display device capable of improving efficiency, reducing power consumption, and improving the lifespan of a device by emitting light to the maximum without forming light absorbed by the polarizing plate. There is this.

An organic light emitting display device of the present invention for solving the problems of the prior art as described above, is formed on a substrate for emitting an organic light emitting device; A reflective polarizing film formed on the organic light-emitting device, a reflective polarizing film (dual brightness enhancement film, DBEF); A cholesteric liquid crystal (CLC) film formed on the reflective polarizing film; A phase retardation plate formed on the cholesteric liquid crystal film; And it characterized in that it comprises a polarizing plate formed on the phase retardation plate.

The organic light emitting display device according to the present invention is capable of removing reflection of external light, so that black can be satisfactorily implemented and has a first effect that can improve contrast.

In addition, the organic light emitting display device according to the present invention, without forming the light absorbed by the polarizing plate, it is possible to emit as much as possible to improve efficiency, reduce power consumption, and improve the life of the device. It works.

1 is a view showing an organic light emitting display device according to the present invention.
2 is a view showing a path of light emitted from the outside and light emitted from the organic light emitting device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided as examples to ensure that the spirit of the present invention is sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And in the drawings, the size and thickness of the device may be exaggerated for convenience. Throughout the specification, the same reference numbers refer to the same components.

1 is a view showing an organic light emitting display device according to the present invention.

Referring to FIG. 1, the element substrate 100 of the organic light emitting display device according to the present invention is divided into a display area and a non-display area, and the display area is divided into a plurality of pixel areas. A thin film transistor TFT is formed in each pixel area, and an organic light emitting device 200 electrically connected to the thin film transistor TFT is formed. On top of the organic light emitting device 200, a reflective polarization film (dual brightness enhancement film, DBEF) 302, a cholesteric liquid crystal (CLC) film 303, a phase retardation plate 304, and a polarizing plate ( 305) are formed by sequentially stacking.

In the device substrate 100, a semiconductor layer 11 including a source region 11a, a channel region 11b and a drain region 11c is formed on an insulating substrate 10. A gate insulating layer 12 is formed on the semiconductor layer 11, and a gate wiring and a gate electrode 13 branched from the gate wiring are formed on the gate insulating layer 12. An interlayer insulating film 14 is formed on the gate wiring and the gate electrode 13.

A data line defining a pixel area by intersecting a gate line with the interlayer insulating layer 14 interposed therebetween, and a source electrode 15 branched from the data line and a drain electrode 16 spaced apart at a predetermined distance from the source electrode 15 ) Is formed. At this time, the source electrode 15 and the drain electrode 16 of the semiconductor layer 11 through the contact hole formed through the interlayer insulating film 14 and the gate insulating film 12 formed on the gate electrode 13 The source region 11a and the drain region 11c are connected. The thin film transistor TFT is formed including the semiconductor layer 11, the gate electrode 13, the source electrode 15 and the drain electrode 16.

A protective layer 17 is formed on the source electrode 15 and the drain electrode 16, and a contact hole exposing the drain electrode 16 is formed on the protective layer 17. The exposed drain electrode 16 is electrically connected to a connection electrode 18 formed on the protective layer 17. A planarization film 19 is formed on the entire surface of the insulating substrate 10 including the thin film transistor TFT, and a contact hole through which the connection electrode 18 is exposed is formed on the planarization film 19.

An organic light emitting device 200 electrically connected to a thin film transistor TFT is formed through a contact hole formed in the planarization layer 19. The organic light emitting device 200 includes a first electrode 20, an organic light emitting layer 22 and a second electrode 23.

In more detail, the first electrode 20 of the organic light emitting device 200 is formed on the exposed connection electrode 18. In the drawing, the first electrode 20 of the organic light emitting device 200 and the drain electrode 16 of the thin film transistor are illustrated to be connected through the connection electrode 18, but the connection electrode 18 is omitted, and the organic light emitting device The first electrode 20 of 200 and the drain electrode 16 of the thin film transistor may be formed by directly contacting the planarization film 19 with contact holes.

On the first electrode 20, a bank pattern 21 exposing the first electrode 20 in units of pixel areas is formed. The organic light emitting layer 22 is formed on the exposed first electrode 20. The organic light emitting layer 22 is composed of a single layer made of a luminescent material, or a hole injection layer, a hole transporting layer, a light emitting material layer, and an electron transport layer to increase luminous efficiency ( electron transporting layer), and an electron injection layer.

A second electrode 23 is formed on the organic light emitting layer 22. When the first electrode 20 is an anode, the second electrode 23 is a cathode, and when the first electrode 20 is a cathode, the second electrode is an anode (anode). A protective layer 210 for protecting display elements is formed on the second electrode 23.

The device substrate 100 and the organic light emitting device 200 of the organic light emitting display device according to the present invention are not limited thereto, and various changes and modifications can be made without departing from the technical idea of the present invention.

At this time, a reflector 301 may be formed under the organic light emitting device 200. That is, a reflective plate 301 may be formed between the organic light emitting device 200 and the device substrate 100. A reflector 301 may be formed under the first electrode 20 of the organic light emitting device 200. In addition, the first electrode 20 may be formed of a reflective film. In addition, the reflector 301 is omitted, and the first electrode 20 or the second electrode 23 may serve as a reflector.

On top of the organic light emitting device 200, a reflective polarization film (dual brightness enhancement film, DBEF) 302, a cholesteric liquid crystal (CLC) film 303, a phase retardation plate 304, and a polarizing plate ( 305) are formed by sequentially stacking. The reflective polarization film (dual brightness enhancement film, DBEF) 302, a cholesteric liquid crystal (CLC) film 303, a phase retardation plate 304, and a polarizing plate 305 are the organic light emitting elements ( It may be formed on the protective layer 210 to protect the display elements of 200).

That is, a reflective polarizing film (DBEF) 302 is disposed on the organic light emitting device 200, and directly on the reflective polarizing film 302 and the reflective polarizing film 302. A cholesteric liquid crystal (CLC) film 303 is formed to contact. In addition, a phase retardation plate 304 is formed on the cholesteric liquid crystal film 303 to be in contact with each other, and is stacked on the phase retardation plate 304 to be in contact with the polarizing plate 305.

The polarizing plate 305 linearly polarizes light. Specifically, the polarizing plate 305 passes light that matches the polarization axis and absorbs light that does not match the polarization axis. That is, when light passes through the polarizing plate 305, it is linearly polarized in the polarization axis direction of the polarizing plate 305.

The phase retardation plate 304 may be a quarter wave plate. At this time, the phase retardation plate 304 may convert linearly polarized light into circularly polarized light. The phase retardation plate 304 may be arranged such that when linearly polarized light flows in the polarization axis direction of the polarizing plate 305, the linearly polarized light becomes circularly polarized to the right. Hereinafter, the light circularly polarized to the right is called right circular polarization. In addition, light circularly polarized to the left is called left circularly polarized light.

In addition, when the right circularly polarized light flows in, the phase delay plate 304 may be arranged such that the right circularly polarized light is linearly polarized in the polarization axis direction of the polarizing plate 305. In addition, when the left circularly polarized light flows in, the phase delay plate 304 may be arranged such that the left circularly polarized light becomes linearly polarized in a direction different from the polarization axis of the polarizing plate 305. When the left circularly polarized light flows in, the phase delay plate 304 may be arranged such that the left circularly polarized light becomes linearly polarized in a direction perpendicular to the polarization axis of the polarizing plate 305.

The cholesteric liquid crystal (CLC) film 303 may selectively transmit or reflect circularly polarized light. The upper surface of the cholesteric liquid crystal film 303 reflects when right-circular polarization is incident. At this time, the upper surface of the cholesteric liquid crystal film 303 is characterized by reflecting by inverting the phase of the right circularly polarized light to the left circularly polarized light. That is, when light circularly polarized to the right is incident on the top surface of the cholesteric liquid crystal film 303, it is reflected as circularly polarized light to the left.

On the other hand, when the left circularly polarized light is incident on the lower surface of the cholesteric liquid crystal film 303, the right circularly polarized light may be transmitted. That is, the cholesteric liquid crystal film 303 has different characteristics on the upper and lower surfaces. Due to this, it may have different characteristics for light emitted from inside and light entering from outside.

In addition, when linearly polarized light is incident on the cholesteric liquid crystal film 303, the linearly polarized light may pass through the cholesteric liquid crystal film 303 and be converted into circularly polarized light. When the linearly polarized light in the polarization axis direction of the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303, the linearly polarized light may be right circularly polarized while transmitting through the cholesteric liquid crystal film 303.

The reflective polarization film (dual brightness enhancement film, DBEF) 302 passes light that matches the polarization axis and reflects light that does not match the polarization axis. The reflective polarizing film 302 differs from the polarizing plate 305 in that it reflects light that does not match the polarization axis.

At this time, among the light emitted from the organic light emitting device 200, light that does not match the polarization axis of the reflective polarizing film 302 is reflected, and is incident on the reflector 301 formed under the organic light emitting device 200. , Reflecting toward the outside, phase delay occurs. Due to this, while light circulates between the reflective polarizing film 302 and the reflecting plate 301, some pass through the reflective polarizing film 302, and the rest repeat the process of re-reflection, and finally the organic light emitting device The light emitted from the 200 may be light that coincides with the polarization axis of the reflective polarizing film 302 and can be emitted to the outside.

When the reflector 301 is omitted, and the first electrode 20 or the second electrode 23 of the organic light emitting device 200 serves as a reflector, light is a reflective polarizing film 302 and the first While circulating between the electrode 20 or the second electrode 23, a part passes through the reflective polarizing film 302, the rest repeats the process of re-reflection, and finally emitted from the organic light emitting device 200 The light becomes light that coincides with the polarization axis of the reflective polarizing film 302 and can be emitted to the outside.

In the conventional organic light emitting display device, a structure for suppressing reflection of light entering from the outside has been studied, but this has a problem that cannot be removed by minimizing reflection of external light. For this reason, it is difficult to implement a complete black state, and there is a disadvantage that the contrast is lowered. In addition, there is a problem that light emitted from the organic light emitting device is lost together in the process of suppressing reflection of external light.

The organic light emitting display device according to the present invention can remove light flowing from the outside and minimize the loss of internal light emitted from the organic light emitting device. Hereinafter, with reference to the drawing showing the path of light, the effect of removing the light coming from the outside and minimizing the loss of internal light emitted from the organic light emitting device will be described.

2 is a view showing a path of light emitted from the outside and light emitted from the organic light emitting device.

Referring to FIG. 2, light flowing from the outside into the organic light emitting display device according to the present invention cannot be emitted again. The external light 400, which is light flowing from the outside, is absorbed by the light passing through the polarizing plate 305 except for light in a direction coinciding with the polarization axis of the polarizing plate 305. That is, only the linearly polarized light 401 in a direction coinciding with the polarization axis of the polarizing plate 305 is transmitted and incident.

The linearly polarized light 401 is incident on the phase delay plate 304. While passing through the phase delay plate 304, the linearly polarized light 401 becomes a right circularly polarized light 402 and is incident on the upper surface of the cholesteric liquid crystal film 303. That is, when the light in the direction coinciding with the polarization axis of the polarizing plate 305 is incident on the phase delay plate 304, which is the quarter wave plate, the linearly polarized light 401 is phase delayed. It passes through the plate 304 and becomes the right circular polarization 402.

When the right circularly polarized light 402 is incident on the upper surface of the cholesteric liquid crystal film 303, it is configured to reflect the left circularly polarized light 403. Therefore, the right circularly polarized light 402 is reflected from the upper surface of the cholesteric liquid crystal film 303, becomes the left circularly polarized light 403, and enters the phase delay plate 304 again.

When the left circularly polarized light 403 is incident on the phase delay plate 304, the phase delay plate 304 transmits the linearly polarized light 404. The linearly polarized light 404 is linearly polarized light 404 in a direction different from a polarization axis of the polarizing plate 305. At this time, the linearly polarized light 404 has a direction perpendicular to the polarization axis of the polarizing plate 305.

Therefore, since the linearly polarized light 404 has a direction perpendicular to the polarization axis of the polarizing plate 305, the linearly polarized light 404 is absorbed by the polarizing plate 305 after being incident on the polarizing plate 305. Thus, the external light 400, which is light introduced from the outside, can be removed without being emitted to the outside. Since the external light 400 is not emitted to the outside again, the organic light emitting display device according to the present invention can improve the implementation and contrast of black.

In addition, loss of light emitted from the organic light emitting device 200 of the organic light emitting display device according to the present invention can be minimized. Some of the internal light 500 which is light emitted from the organic light emitting device 200 passes through the reflective polarizing film 302 and is linearly polarized 501. The linearly polarized light 501 is linearly polarized light in the same direction as the polarization axis of the reflective polarizing film 302. The light 504 except for the linearly polarized light 501 is reflected by the reflective polarizing film 302 and is incident on the reflective plate 301 under the organic light emitting device 200.

The light 504 reflected from the reflective polarizing film 302 circulates (RECYCLE) between the reflective plate 301 and the reflective polarizing film 302 while linearly polarizing a part while passing through the reflective polarizing film 302 And the rest is repeated. Accordingly, the light reflected from the reflective polarizing film 585 may be linearly polarized 501 while finally passing through the reflective polarizing film 302. Due to this, the light emitted from the organic light emitting device 200 can minimize its loss and allow most of the light to be emitted to the outside.

The linearly polarized light 501 passing through the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303. The linearly polarized light 501 may be incident on the lower surface of the cholesteric liquid crystal film 303 and may be transmitted to the right circularly polarized light 502 while passing through the cholesteric liquid crystal film 303.

That is, when linearly polarized light enters the lower surface of the cholesteric liquid crystal film 303, it can be transmitted through circularly polarized light. At this time, when the linearly polarized light 501 in the polarization axis direction of the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303, the linearly polarized light 501 passes through the cholesteric liquid crystal film 303. It becomes right-circular polarization 502.

The right circularly polarized light 502 is incident on the phase delay plate 304. When the right circularly polarized light 502 is incident on the phase delay plate 304, it is transmitted through the linearly polarized light 503. The linearly polarized light 503 is linearly polarized light 503 in a direction coinciding with the polarization axis of the polarizing plate 305.

Due to this, since the light 503 emitted from the organic light emitting element 200 that has passed through the phase delay plate 304 has the same direction as the polarization axis of the polarizing plate 305, it may pass through the polarizing plate 305. Can be. That is, the internal light 500, which is light emitted from the inside, is not absorbed by the polarizing plate 305 and can be all emitted to the outside.

Therefore, the organic light emitting display device according to the present invention can remove reflection of external light, thereby realizing black satisfactorily, improving contrast, and forming light absorbed by the polarizing plate, and maximizing emission It can improve the efficiency, reduce the power consumption, and improve the life of the device.

Through the above description, those skilled in the art will appreciate that various changes and modifications are possible without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the scope of the claims.

100: element substrate
200: organic light emitting device
301: reflector
302: reflective polarizing film
303: cholesteric liquid crystal film
304: phase delay plate
305: polarizing plate

Claims (9)

An organic light emitting element formed on a substrate and emitting light;
A reflective polarizing film formed on the organic light-emitting device, a reflective polarizing film (dual brightness enhancement film, DBEF);
A cholesteric liquid crystal (CLC) film formed on the reflective polarizing film;
A phase retardation plate formed on the cholesteric liquid crystal film; And
It includes a polarizing plate formed on the phase retardation plate,
The cholesteric liquid crystal film is an organic electroluminescent display device characterized in that when the right circularly polarized light enters the upper surface, the phase is reversed and reflected by the left circularly polarized light.
delete According to claim 1,
Light passing through the polarizing plate and flowing from outside is linearly polarized,
The linearly polarized light transmits the phase retardation plate and is an organic light emitting display device, characterized in that it becomes right-circularly polarized light.
According to claim 1,
When the left circularly polarized light is incident on the phase retardation plate, the organic light emitting display device is characterized in that it transmits linearly polarized light in a direction perpendicular to the polarization axis of the polarizing plate.
According to claim 1,
When the linearly polarized light enters the cholesteric liquid crystal film, the organic light emitting display device is characterized in that it transmits as circularly polarized light.
The method of claim 5,
When the linear polarization of the cholesteric liquid crystal film in the same direction as the polarization axis of the reflective polarizing film is incident on the lower surface, an organic electroluminescence display device characterized in that it transmits with right circular polarization.
According to claim 1,
The phase retardation plate is an organic electroluminescence display device characterized in that when the right circularly polarized light is incident, it is transmitted through linearly polarized light in the same direction as the polarization axis of the polarizing plate.
According to claim 1,
An organic electroluminescent display device, characterized in that a reflective plate is further formed between the organic light emitting element and the substrate.
The method of claim 8,
The light emitted from the organic light emitting element is transmitted through or reflected from the reflective polarizing film,
The organic light emitting display device, characterized in that the light reflected from the reflective polarizing film is incident on the reflective plate and reflected, and then incident on the reflective polarizing film.

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